<template>
    <div class="Child">
        <p>这里是Child组件</p>
        {{sum}}
    </div>
</template>

<script>
import { ref } from 'vue'
export default {
    name: 'Child',
    components: {},
    setup(){
        let sum = ref(0)
        return new Promise((resolve)=>{
            setTimeout(()=>{
                resolve({sum})
            },3000)
        })
    }
}
</script>

<style>
.Child{
    background-color: skyblue;
    padding: 10px;
}
</style>